We demonstrate that the selectivity of microchip electrophoresis separations is greatly improved by the presence of organically modified silica (Ormosil) sols in the run buffer. A negatively-charged N-(trimethoxysilylpropyl)ethylenediamine triacetic-acid (TETT)-based sol is used for improving the selectivity between nitroaromatic explosives and a methyltrimethoxysilane (MTMOS)-based sol is employed for enhancing the microchip separation of environmental pollutants, aminophenols. These sols are added to the run buffer and act as pseudostationary phases. Their presence in the run buffer changes the apparent mobility of studied solutes, and leads to a higher resolution. The observed mobilities changes reflect the interactions between the Ormosil sols and the solutes. Relevant experimental variables have been characterized and optimized. The diverse chemistry of Ormosil sols should be extremely useful for tailoring the selectivity of a wide range of electrophoresis microchip separations.
Bibliographical noteFunding Information:
This research was supported by grants from the US Dept. of Justice-MIPT Program, the Office of Naval Research (Award Number N00014-02-1-0213) and the United States-Israel Binational Science Foundation (BSF), (Award No. 1999199). M.P. is grateful to the Japanese Ministry for Education, Culture, Sports, Science and Technology (MEXT) for funding thought ICYS program.
- Environmental pollutants
- Microchip capillary electrokinetic chromatography